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 <meta name="date" content="2004-01-22" />
 <title>VqmCalc</title>
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<h1>VqmCalc</h1>

<h2>&Uuml;bersicht</h2>
<b>Autor:</b> Lefungus<br />
<b>Version:</b> 0.21<br />
<b>Download:</b> <a href="http://perso.wanadoo.fr/reservoir/dl/VqmCalc-0.21.rar" target="_blank">VqmCalc-0.21</a> / <a href="http://perso.wanadoo.fr/reservoir/dl/VqmCalcSrc-0.21.rar" target="_blank">Quellcode</a><br />
<b>Kategorie:</b> Videovergleich<br />
<b>Anforderungen:</b> YV12 Farbformat<br />
<hr>
<h2>Description</h2>
<p><font face="verdana, arial, helvetica" size="2">The compare function of AviSynth,
calculates psnr from two clips. The following method (called VQM) should be a
better video quality metrics than psnr. It is based on the following report:<br>
<br>
<a href="http://ise.stanford.edu/class/ee392j/projects/xiao_report.pdf" target="_blank">http://ise.stanford.edu/class/ee392...xiao_report.pdf</a><br>
<br>
It is not exactly the same as in the white-paper as some vital informations are
lacking like the matrix we need to use for spatial masking.<br>
In this filter, i use MPEG Matrix with hope it reflects a bit Human Visual
System.<br>
No temporal masking is implemented in this method.<br>
<br>
A few experiments were done with a little clip encoded with xvid at constant
quant2/quant4/quant6 and quant2 with VHQ1.<br>
<br>
Keep in mind these results may not reflect video quality<br>
<br>
Mean VQM:<br>
Quant2: 37.16<br>
Quant4: 52.58<br>
Quant6: 63.12<br>
Quant2+VHQ1: 37.74<br>
<br>
More points (may) means less quality. It seems to scale well with Quants but it
doesn't like VHQ.<br>
<br>
It will only work with YV12. And it seems to not works with B-Frames.<br>
The clip must be mod8. If not it may crash.<br>
Another bugs i've encountered are:<br>
-May crash when the log already exist<br>
-May crash during the clip, try again until it works<br>
<br>
I hope you're not afraid to test it.</font>
<p><font face="verdana, arial, helvetica" size="2"><br>
<b>an example:</b></font></p>
<pre>a=AVIsource(&quot;J:\Video\Source.avs&quot;)
b=AVIsource(&quot;J:\Video\Quant6.avi&quot;)
return VqmCalc(a,b,&quot;results.log&quot;)</pre>
<p><font face="verdana, arial, helvetica" size="2"><br>
PS: I use fdct_mmx from xvid sources, so i guess i need to release it GPL, and
include GPL headers. I'm not sure if i can, because it's inspired from a white
paper. I'll be glad to receive any help on this subject.<br>
</font></p>
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